D8056: Improve usability of "Open With" dialog by adding option to filter the application tree

[Nathaniel Graham]

ngraham added reviewers: Frameworks, VDG.

REPOSITORY
  R241 KIO

REVISION DETAIL
  https://phabricator.kde.org/D8056

To: simgunz, dfaure, #frameworks, #vdg
Cc: alexeymin, #frameworks